Plant tissues - epidermis, palisade mesophyll and spongy mesophyll
The structure of a leaf
Plant leaves are adapted for A chemical process used by plants to make glucose and oxygen from carbon dioxide and water, using light energy. Oxygen is produced as a by-product of photosynthesis. Algae subsumed within plants and some bacteria are also photosynthetic., and the exchange of gases required for the process. The structure of the tissues is related to their functions in the plant.
Absorbing light energy
The Plant tissue containing closely packed cells in the upper layer of a leaf. layer of the leaf is adapted to absorb light efficiently. The cells:
- are packed with many Contains the green pigment chlorophyll; the site of photosynthesis.
- are column-shaped and arranged closely together
- towards the upper surface of the leaf
Gas exchange
The plant tissue in a leaf which has loosely packed cells and air spaces between them to allow gas exchange. tissue is packed loosely for efficient gas exchange. The spongy mesophyll cells are covered by a thin layer of water. Gases dissolve in this water as they move into and out of the cells.
When the plant is photosynthesising during the day, these features allow carbon dioxide to diffuse into the spongy mesophyll cells, and oxygen to diffuse out of them.
To enter the leaf, gases diffuse through small pores called stomata. As the stomata open, water is lost by the process of The loss of water from leaves by evaporation through the stomata.. Closing the stomata helps to control water loss.